ML24074A355
| ML24074A355 | |
| Person / Time | |
|---|---|
| Issue date: | 03/14/2024 |
| From: | John Wise NRC/NRR/DNRL/NLRP |
| To: | |
| References | |
| Download: ML24074A355 (1) | |
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RIC 2024 Hybrid U.S. Nuclear Regulatory Commission 36th Annual Regulatory Information Conference MARCH 12-14, 2024
- nrcric2024 www.nrc.gov ADAPTING TO A CHANGING LANDSCAPE Managing Selective Leaching during Long-Term Operation John Wise, Senior Technical Advisor Division of New and Renewed Licenses Office of Nuclear Reactor Regulation, U.S. NRC 1
RIC 2024 Hybrid U.S. Nuclear Regulatory Commission 36th Annual Regulatory Information Conference MARCH 12-14, 2024
- nrcric2024 www.nrc.gov Selective Leachingpreferential corrosion of the more active (less noble) component of an alloy Dealloying Graphitic corrosion De-alumification De-zincification Oxidation of iron matrix in gray cast iron rupture Buried cast iron municipal gas main May compromise structural integrity with little change in appearance 2
Commonly used susceptible materials Cast irons Copper alloys
(>15%Zn or 8%Al)
RIC 2024 Hybrid U.S. Nuclear Regulatory Commission 36th Annual Regulatory Information Conference MARCH 12-14, 2024
- nrcric2024 www.nrc.gov Operating ExperienceExamples 1984 Cast iron in salt water Through-wall corrosion of component cooling heat exchanger 1993 Aluminum bronze in brackish water Leakage in service water valve bodies Began 1987 Aluminum bronze in raw water Cracking/
leakage in essential cooling water components 2019 Cast iron in soil Rupture of fire protection piping during pump surveillance Nonnuclear Cast iron water distribution systems, buried natural gas piping Aluminum bronze in seawater (Navy),
desalinization plants IN 84-71 IN = NRC information notice EDG = emergency diesel generator IN 94-59 IN 20-04 3
2022 Brass in uncontrolled indoor air EDG radiator leak
RIC 2024 Hybrid U.S. Nuclear Regulatory Commission 36th Annual Regulatory Information Conference MARCH 12-14, 2024
- nrcric2024 www.nrc.gov Regulatory Response Oversight of the plant-specific issue Generic communications to the industry Informed the industry of operating experience; licensees expected to review and consider actions to avoid similar issues Revised guidance for license renewal aging management programs (AMPs)
Generic Aging Lessons Learned (GALL) Report NUREG-1800 (initial renewal), NUREG-2191 (subsequent renewal) 4
RIC 2024 Hybrid U.S. Nuclear Regulatory Commission 36th Annual Regulatory Information Conference MARCH 12-14, 2024
- nrcric2024 www.nrc.gov Selective Leaching of Materials AMP
- One-time inspection (before 40 years)
- Visual
- Hardness
- Sample based
- Added detail: sample size, timing, acceptance criteria
- Introduced alternative mechanical methods (chipping, scraping) 2001, 2005
- Added periodic inspections for aggressive environments
- Defined corrective actions (e.g., sample expansion)
- Hardness testing replaced with mechanical and destructive exams 2010 NUREG-1800 NUREG-2191 2017 To verify absence of selective leaching 5
To manage aging (rather than demonstrating absence of aging)
RIC 2024 Hybrid U.S. Nuclear Regulatory Commission 36th Annual Regulatory Information Conference MARCH 12-14, 2024
- nrcric2024 www.nrc.gov Plant with significant history of selective leaching of aluminum bronze in essential cooling water system Leaks, seepage, cracking
~350 susceptible castings, 3,400 welds Case Study: Plant-Specific License Renewal AMP Visual inspections Destructive examinations Proactive, one time Reactive, when leaks discovered Ultrasonic examinations Time-of-flight diffraction method Structural integrity evaluations 6
RIC 2024 Hybrid U.S. Nuclear Regulatory Commission 36th Annual Regulatory Information Conference MARCH 12-14, 2024
- nrcric2024 www.nrc.gov Lessons Plant-specific aging management approaches have often been needed to address unique circumstances NRC communications and guidance provide the industry the necessary information and a generically acceptable framework to create a strategy for long-term operation Ongoing Activities Updating NUREG-2191 AMP to address recent operating experience (aging of coated buried piping, malleable iron)
Engaging with the industry on its proposed risk-informed approach 7